What is the definition of physics?

1.the application of energy to an object in order to move it
2.the movement of an object from one place to another
3.having to do with another, such as position or size
4.the study of the natural world and its laws
5.the larger SI unit of measuring force, equal to the force necessary to accelerate 1 kilogram at the rate of 1 meter per second squared

4. the study of the natural world and its laws

The correct definition of physics is option 4: the study of the natural world and its laws.